Liquid crystal display panel and active device array substrate thereof

ABSTRACT

An active device array substrate including a substrate, a plurality of scan lines, a plurality of data lines, and a plurality of pixel units, each of the pixel units formed between every neighboring two of the scan lines and data lines is provided. Each of the pixel units includes a first active device, a first pixel electrode electrically connected to a corresponding scan line and a corresponding data line through the first active device, a second active device, a second pixel electrode electrically connected to a corresponding scan line and a corresponding data line through the first active device, a second active device and a second pixel electrode electrically connected to a corresponding scan line and a corresponding data line through the second active device. The first pixel electrode has a surface area different from that of the second pixel electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims thepriority benefit of a U.S. application Ser. No. 13/026,308, filed onFeb. 14, 2011, which is a divisional application of U.S. applicationSer. No. 11/740,295, filed on Apr. 26, 2007, U.S. Pat. No. 7,916,233.The U.S. application Ser. No. 11/740,295 claims the priority benefit ofTaiwan application serial no. 95140666, filed on Nov. 3, 2006. Theentirety of each of the above-mentioned patent applications is herebyincorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a liquid crystal display(LCD) panel and an active device array substrate thereof, in particular,to a LCD panel for efficiently promoting displaying quality.

2. Description of Related Art

Generally, the optical displaying effect of the conventional verticallyaligned mode LCD is achieved by means of electrically controlledbirefringence. In other words, the optical displaying effect of theconventional vertically aligned mode LCD is caused by the phaseretardation of lights. When the phase retardation changes with theapplied voltages, the images vary in brightness or darkness.

For example, a multi-domain vertically aligned (MVA) LCD has a pluralityof protrusions/slits on a color filter substrate or a thin filmtransistor (TFT) array substrate thereof. The protrusions or slits areconfigured for controlling liquid crystal molecules arranged inmulti-directions, thus obtaining a plurality of domains. Such theMVA-LCD can display images with wide view angle. However, transmittanceof the MVA-LCD varies as the viewing angle changes, thus causing graylevels of displayed images varied accordingly. In other words, a viewerwill see images of different brightness, when viewing the MVA-LCD atdifferent angles.

For a twisted nematic (TN) LCD, the arrangement of the liquid crystalmolecules are asymmetrically such that the viewer will see images ofdifferent brightness or even gray level inversion when viewed at variousviewing angles. As shown in FIG. 1, when a viewer sees the image at aviewing angle θ=0°, the transmittance decrease but the driving voltageincreases. While the viewer sees the image at a viewing angle θ=45°, or60°, the transmittance inversely increases in certain ranges, forexample at the peak A shown in FIG. 1, as the driving voltage increases.The displaying quality is not good. Hence, there is a need forimprovement in this area.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an active device arraysubstrate in a single pixel unit of the active array substrate, whereinpixel electrodes thereof have different charging ratios.

The present invention is also directed to an active device arraysubstrate having pixel electrodes of different areas in a single pixelunit.

The present invention is still directed to an LCD panel having an activedevice array substrate for obtaining better displaying quality than thatof conventional LCD panels.

For achieving the aforementioned objects or others, the presentinvention provides an active device array substrate. The active arraysubstrate includes a substrate, a plurality of scan lines, a pluralityof data lines, and a plurality of pixel units. The scan lines, the datalines and the pixel units are disposed over the substrate. Each pixelunit is formed between every neighboring two of the scan lines and datalines and includes a first active device, a first pixel electrode, afirst resistant device, a second active device, and a second pixelelectrode. The first pixel electrode is electrically connected to acorresponding scan line and a corresponding data line through the firstactive device. The first resistant device is electrically connectedbetween the first active e device and the first pixel electrode. Thesecond pixel electrode is electrically connected to a corresponding scanline and a corresponding data line through the second active device.

According to an embodiment of the present invention, the foregoingactive device array substrate further includes a second resistant deviceelectrically connected between the second active device and the secondpixel electrode.

According to an embodiment of the present invention, the foregoingactive device array substrate further includes a shielding metal layerdisposed under the second resistant device.

According to an embodiment of the present invention, the foregoing firstresistant device and second resistant device comprise photosensitivematerials.

According to an embodiment of the present invention, the foregoing firstresistant device and second resistant device comprise amorphous silicon.

The present invention further provides an LCD panel including anabove-described active device array substrate, an opposite substrate,and a liquid crystal layer. The opposite substrate is disposed over theactive device array substrate, and the liquid crystal layer is disposedbetween the active device array substrate and the opposite substrate.

According to an embodiment of the present invention, the oppositesubstrate can be a color filter substrate.

The present invention further provides an active device array substrateincluding a substrate, a plurality of scan lines, a plurality of datalines, and a plurality of pixel units. The scan lines, the data lines,and the pixel units are disposed over the substrate. Each pixel unit isformed between every neighboring two of the scan lines and data linesand includes a first active device, a first pixel electrode, a secondactive device, and a second pixel electrode. The first pixel electrodeis electrically connected to a corresponding scan line and acorresponding data line through the first active device. The secondpixel electrode is electrically connected to a corresponding scan lineand a corresponding data line through the second active device. Thefirst pixel electrode has a surface area different from that of thesecond pixel electrode.

According to an embodiment of the present invention, the first electrodehas an surface area of 0.2 to 0.8 times of that of the second pixelelectrode.

The present invention further provides an LCD panel including theaforementioned active device array substrate having first pixelelectrodes and second electrodes having different surface areas, anopposite substrate, and a liquid crystal layer. The opposite substrateis disposed over the active device array substrate, and the liquidcrystal layer is disposed between the active device array substrate andthe opposite substrate.

According to an embodiment of the present invention, the oppositesubstrate can be a color filter substrate.

The present invention further provides an active device array substrateincluding a substrate, a plurality of scan lines, a plurality of datalines, and a plurality of pixel units. The scan lines, the data linesand the pixel units are disposed over the substrate. Each pixel unit isformed between every neighboring two of the scan lines and data linesand includes a double drain active device, a first pixel electrode, afirst resistant device, and a second pixel electrode. The double drainactive device includes a first active device and a second active device.The first pixel electrode is electrically connected to a correspondingscan line and a corresponding data line through the first active deviceof the double drain active device. The first resistant device iselectrically connected between the first active e device and the firstpixel electrode. The second pixel electrode is electrically connected toa corresponding scan line and a corresponding data line through thesecond active device of the double drain active device.

The present invention further provides an LCD panel including anabove-described active device array substrate, an opposite substrate,and a liquid crystal layer. The opposite substrate is disposed over theactive device array substrate, and the liquid crystal layer is disposedbetween the active device array substrate and the opposite substrate.

The present invention further provides an active device array substrateincluding a substrate, a plurality of scan lines, a plurality of datalines, and a plurality of pixel units. The scan lines, the data lines,and the pixel units are disposed over the substrate. Each pixel unit isformed between every neighboring two of the scan lines and data linesand includes a double drain active device, a first pixel electrode, anda second pixel electrode. The double drain active device includes afirst active device and a second active device. The first pixelelectrode is electrically connected to a corresponding scan line and acorresponding data line through the first active device of the doubledrain active device. The second pixel electrode is electricallyconnected to a corresponding scan line and a corresponding data linethrough the second active device of the double drain active device. Thefirst pixel electrode has a surface area different from that of thesecond pixel electrode.

The present invention further provides an LCD panel including theaforementioned active device array substrate having first pixelelectrodes and second electrodes having different surface areas, anopposite substrate, and a liquid crystal layer. The opposite substrateis disposed over the active device array substrate, and the liquidcrystal layer is disposed between the active device array substrate andthe opposite substrate.

The first pixel electrode and the second electrode of the active devicearray substrate have different surface areas, or the substrate has afirst resistant device electrically connected between the first activedevice and the first pixel electrode. In this way, in a single pixelunit, after being charged, the first pixel electrode and the secondpixel electrode obtain different voltage levels. As such, liquid crystalmolecules respectively corresponding to the first pixel electrode andthe second pixel electrode are driven by different voltages, thus thetransmittances thereof are accordingly different from each other.Therefore, different transmittances can compensate each other, thus theLCD panel of the present invention can efficiently reduce the problem ofcolor shift.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a schematic diagram of a conventional LCD illustrating arelationship between the driving voltage and the transmittance.

FIG. 2 is a schematic diagram for illustrating an LCD panel according toa first embodiment of the present invention.

FIG. 3A is a schematic diagram for illustrating an active device arraysubstrate according to the first embodiment of the present invention.

FIG. 3B is a circuit diagram of active device array substrate accordingto the first embodiment of the present invention.

FIG. 3C is a partial cross-sectional view of FIG. 3A along line A-A′.

FIG. 4 is a schematic diagram showing a curve for illustrating theresistance feature of the amorphous silicon material according to thefirst embodiment of the present invention.

FIG. 5 shows schematic diagrams according to the first embodiment of thepresent invention illustrating a relationship between the drivingvoltage and the transmittance, when viewed at a viewing angle θ=60°.

FIG. 6 is a diagram showing average curves for illustratingrelationships between driving voltages and transmittances of eachrespective view angle.

FIG. 7 is a schematic diagram for illustrating another active devicearray substrate according to the first embodiment of the presentinvention.

FIG. 8A is a schematic diagram for illustrating a shielding metal layeraccording to the first embodiment of the present invention.

FIG. 8B is a partial cross-sectional view of FIG. 8A along line B-B′.

FIG. 9A is a schematic diagram for illustrating an active device arraysubstrate according to a second embodiment of the present invention.

FIG. 9B is a circuit diagram of active device array substrate accordingto the second embodiment of the present invention.

FIG. 10 is a schematic diagram according to the second embodiment of thepresent invention, illustrating a relationship between driving voltageand transmittance, when viewed at a viewing angle θ=60°.

FIG. 11 is a schematic diagram for illustrating another active devicearray substrate according to the second embodiment of the presentinvention.

FIG. 12 is a schematic diagram for illustrating a shielding metal layeraccording to the first embodiment of the present invention.

FIG. 13 is a schematic diagram for illustrating an active device arraysubstrate according to a third embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts.

First Embodiment

FIG. 2 is a schematic diagram for illustrating an LCD panel according toa first embodiment of the present invention. Referring to FIG. 2, an LCDpanel 100 according to the present invention includes an active devicearray substrate 110, an opposite substrate 120, and a liquid crystallayer 130. The liquid crystal layer 130 is disposed between the activedevice array substrate 110 and the opposite substrate 120. Generally, abacklight module (not shown) is often disposed under the LCD panel 100that is usually not capable of emitting light by itself, for providing aplane light source thereto. The opposite substrate 120 is a color filtersubstrate. In such a way, the LCD panel can achieve the purpose of fullcolor display. A twisted nematic (TN) LCD is exemplified here-below toillustrate the LCD panel 100 of the first embodiment according to thepresent invention. However, it should be noted that the LCD panel 100 isnot limited as a TN LCD. For example, the LCD panel 100 can also be ofvertically aligned (VA) mode or in-plane switching (IPS) mode as well.

FIG. 3A is a schematic diagram for illustrating an active device arraysubstrate according to the first embodiment of the present invention.FIG. 3B is a circuit diagram of active device array substrate accordingto the first embodiment of the present invention. Referring to FIGS. 3Aand 3B, the active device array substrate 110 includes a substrate 112,a plurality of scan lines 114, a plurality of data lines 116, and aplurality of pixel units P (only one is illustrated in FIG. 3A). Thescan lines 114 and the data lines 116 are disposed over the substrate112 to define positions of the pixel units P. The pixel units P areoften arranged in an array on the substrate 112.

The pixel unit P as shown in FIG. 3A mainly includes a double drainactive device. Referring to FIG. 3B, in the operation of the circuit,the circuit of the double drain active device is equal to the equivalentcircuit of the first active device and the second active device. Ofcourse, the pixel unit P may be selectively designed as the unitincluding two independent active devices. Referring to FIGS. 3A and 3Bsimultaneously, the pixel unit P includes a double drain active device(including the first active device and the second active device), afirst pixel electrode P1, a first resistant device R1, and a secondpixel electrode P2. Particularly, the first active device having thedrain D1 and the second active device having the drain D2 may have thesame gate and source. The first pixel electrode P1 is electricallyconnected to a corresponding scan line 114 and a corresponding data line116 through the first active device T1. The second pixel electrode P2 iselectrically connected to a corresponding scan line 114 and acorresponding data line 116 through the second active device T2. Thefirst pixel electrode P1 and the second pixel electrode P2 usuallyoverlay a common line 118 to construct a storage capacitor C_(st). Thecommon line 118 can be coupled to a reference voltage source.

It should be noted that the first resistant device R1 is electricallyconnected between the first active device T1 and the first pixelelectrode P1. Specifically, the resistance of the first resistant deviceR1 is preferably within a range, e.g., 10 ⁴ to 10⁹Ω, and preferablycomprised of a photosensitive material, e.g., amorphous silicon.

FIG. 3C is a partial cross-sectional view of FIG. 3A along line A-A′.Referring to FIG. 3C, in an embodiment of the present invention, a gatedielectric layer GI can be formed on the substrate 112, and the firstresistant device R1 (amorphous silicon) is disposed on the gatedielectric layer GI. It should be noted that the first resistant deviceR1 can be fabricated together with channel layers (not shown) ofrespectively the first active device T1 and the second active device T2,without adding an extra mask processing step. Furthermore, a secondmetal layer M2 is disposed to cover both sides of the first resistantdevice R1. In order to decrease the resistance between the metalmaterial and the amorphous silicon material, an ohm contact layer L1 mayalso be disposed between the second metal layer M2 and the firstresistant device R1. According to an object of the first embodiment, thesecond metal layer M2, the data lines 116, and source/drain pairs of thefirst active device T1 and the second active device T2 respectively areformed in a single process step. Furthermore, a passivation layer PA canbe disposed to cover the first resistant device R1 and the second metallayer M2, while the first pixel electrode P1 is disposed on thepassivation layer PA.

Specifically, according to an embodiment of the present invention, thepreferable thinness of the amorphous layer is 1000 Å, and a length/widthratio of about 21/5. FIG. 4 shows a curve for illustrating theresistance characteristic of the amorphous silicon material according tothe first embodiment of the present invention. As can be seen from theFIG. 4, resistance of the amorphous silicon material dramaticallydecreases when illuminated by light. After the light intensity reaches acertain value, the resistance of the amorphous material becomes stable.Such a resistance may be approximately equal to a resistance of thechannel layer of the first active device T1 and the second active deviceT2. In practice, the light can be provided by a backlight module.

When a voltage signal is input from the data line 116 to the first pixelelectrode P1 and the second pixel electrode P2, the first resistantdevice R1 causes the first pixel electrode P1 to have less chargescharged than that of the second pixel electrode P2. As such, a chargingratio of the first pixel electrode P1 is lower than the second pixelelectrode P2. Accordingly, liquid crystal molecules corresponding to asingle pixel unit P are driven by two different strengths electricfield, thus these liquid crystal molecules are driven to exhibitdifferent oblique degrees.

Taking a 14 inches LCD panel 100 having a resolution of 1024×768 as anexample, when the active devices have a gate-source voltage V_(gs)=25V,and a drain-source V_(ds)=10V, a conducting current I_(on)=1.806 μA, anda sum of the storage capacitance C_(st) and a liquid crystal capacitanceC_(lc) equal to 0.4768 pF, and the response time T_(on)=21 μs:

operation load R=R _(on) =V _(ds) /I _(on)=10/1.806=5.537 MΩ

delay time τ=R _(on)×(C _(st) +C _(lc))=5.537×0.4768=2.64 μs

${{Charging}\mspace{14mu} {Ratio}} = {\sqrt{\frac{1 - ^{- \frac{21u}{2.64u}}}{1 + ^{- \frac{21u}{2.64u}}}} = {99.96\%}}$

According to the above conditions, the charging ratio is 99.96%. If aresistance Rs is applied between the active device and the pixelelectrode, for example Rs=23.52MΩ:

operation load R=R _(on) +Rs=5.537+23.52=10/1.806=29.057 MΩ

delay time τ=R×(C _(st) +C _(lc))=29.057×0.4768=13.854 μs

${{Charging}\mspace{14mu} {Ratio}} = {\sqrt{\frac{1 - ^{- \frac{21u}{13.854u}}}{1 + ^{- \frac{21u}{13.854u}}}} = {79.99\%}}$

In such a way, the charging ratio becomes 79.99%. Therefore, thecharging ratio of the pixel electrode can be adjusted according topractical demands. In this way, the charging ratio of the first pixelelectrode P1 can be adjusted to about 80% of the charging ratio of thesecond pixel electrode P2. Referring to FIG. 5, curve 1 is acharacteristic diagram showing relationship between voltage andtransmittance corresponding to the area of the first pixel electrode P1,and curve 2 is a characteristic diagram showing relationship betweenvoltage and transmittance corresponding to the area of the second pixelelectrode P2. By compensating each other, the curves 1 and 2 can obtaina relatively flat averaging curve AVG. In other words, when a viewerviews the images from an oblique angle about 0° to 60°, the problem ofinversely increasing transmittance may be effectively reduced when thedriving voltage increase as in the case of the conventional art.

FIG. 6 is a diagram showing average curves for illustratingrelationships between driving voltages and transmittances of eachrespective view angle. Referring to FIG. 6, it is shown that each ofaveraging curves corresponding to respective oblique viewing angles,θ=30°, 45°, 60° is relatively flatter. Therefore, the viewing effectsimilar to the frontal view can be achieved regardless of the viewerviewing angle. As such, the displaying quality can be effectivelypromoted.

FIG. 7 is a schematic diagram for illustrating another active devicearray substrate according to the first embodiment of the presentinvention. Referring to FIG. 7, the active device array substrate 110can further include a second resistant device R2. The second resistantdevice R2 is electrically connected between the second pixel electrodeP2 and the second active device T2. In this way, first pixel electrodeP1 and second pixel electrode P2 having different charging ratios canalso be obtained.

FIG. 8A is a schematic diagram for illustrating a shielding metal layeraccording to the first embodiment of the present invention. Referring toFIG. 8A, for further adjusting the transmittances of the first pixelelectrode P1 and the second pixel electrode P2, the active device arraysubstrate 110 according to the present invention further includes ashielding metal layer M1 disposed under the second resistant device R2.The shielding metal layer M1 is adapted for shielding light from abacklight module (not shown), thus avoiding the second resistant deviceR2 from being illuminated. Therefore, the second resistant device R2 hasa resistance higher than that of the first resistant device R1.Therefore, the first pixel electrode P1 and the second pixel electrodeP2 having different charging ratios can also be obtained.

FIG. 8B is a partial cross-sectional view of FIG. 8A along line B-B′.Referring to FIG. 8B, according to an embodiment of the presentinvention, the shielding metal layer M1 is disposed on the substrate112. It should be noted that the shielding metal layer M1 can befabricated together with the scan line 114, a gate GI of the firstactive device T1, a gate G2 of the second active device T2, and thecommon line 118, without an additional mask processing step. Moreover,the gate dielectric layer GI covers the shielding metal layer M1, whilethe second shielding metal layer M2 is disposed at both sides of thesecond resistant device R2. An ohm contact layer L2 is disposed betweenthe second shielding metal layer M2 and the second resistant device R2.The passivation layer PA covers the second resistant device R2 and thesecond shielding metal layer M2, while the first pixel electrode P1 isconfigured on the passivation layer PA.

Second Embodiment

FIG. 9A is a schematic diagram for illustrating an active device arraysubstrate according to a second embodiment of the present invention.FIG. 9B is a circuit diagram of active device array substrate accordingto the second embodiment of the present invention. The active devicearray substrate 210 described therein is similar to the active devicearray substrate 110 according to the first embodiment of the presentinvention, the main difference between them is that: the active devicearray substrate 210 is adapted for a VA LCD panels, includingmulti-domain vertically alignment (MVA) LCD panels, and patternedvertical alignment (PVA) LCD panels.

Taking an MVA LCD panel as an example, the active device array substrate210 is illustrated in details. In order to have the liquid crystalmolecules arranged in multi-directions for the purpose of obtaining awider viewing angle, many slits S as shown in FIG. 9A are formed on thefirst pixel electrode P1 and the second pixel electrode P2. Further, thefirst resistant device R1 is electrically connected between the firstactive device T1 and the first pixel electrode P1. As such, a chargingratio of the first pixel electrode P1 can be adjusted to some degree todiffer from the charging ratio of the second pixel electrode P2, e.g.,the charging ratio of the first pixel electrode P1 is adjusted to 85% ofthe charging ratio of the second pixel device P2.

Referring to FIG. 10, the curve 1 is a characteristic diagram showingrelationship between the voltage and the transmittance corresponding tothe area of the first pixel electrode P1, and the curve 2 is acharacteristic diagram showing relationship between the voltage and thetransmittance corresponding to the area of the second pixel electrodeP2. By compensating each other, the curves 1 and 2 can obtain arelatively flat averaging curve AVG. In other words, the problem ofcolor shift at the viewing angle of θ=60° can be effectively reduced,and thus displaying quality can be improved.

FIG. 11 is a schematic diagram for illustrating another active devicearray substrate according to the second embodiment of the presentinvention. Referring to FIG. 11, the active device array substrate 210can further include a second resistant device R2. The second resistantdevice R2 is electrically connected between the second pixel electrodeP2 and the second active device T2. In this way, first pixel electrodeP1 and second pixel electrode P2 having charging ratios different fromeach other can also be obtained.

FIG. 12 is a schematic diagram for illustrating a shielding metal layeraccording to the first embodiment of the present invention. Referring toFIG. 12, for further adjusting the transmittances of respective thefirst pixel electrode P1 and the second pixel electrode P2, the activedevice array substrate 210 according to the present invention furtherincludes a shielding metal layer M1 disposed under the second resistantdevice R2. The shielding metal layer M1 is adapted for shielding lightfrom a backlight module (not shown), thus avoiding the second resistantdevice R2 from being illuminated. Therefore, the second resistant deviceR2 has a resistance higher than that of the first resistant device R1that is being illuminated. Therefore, the first pixel electrode P1 andthe second pixel electrode P2 having different charging ratios can alsobe obtained.

Third Embodiment

An LCD panel according to the third embodiment of the present inventionis illustrated below. The LCD panel according to the third embodiment issimilar to the LCD panel of the first embodiment of the presentinvention, the main difference between them is that: the areas of thefirst pixel electrode and the second pixel electrode are different, andit is unnecessary to dispose a first resistant device and a secondresistant device as disclosed in the first embodiment. Of course, such afirst resistant device and second resistant device can be optionallydisposed on the substrate, and it is not intended to limit the scope ofthe present invention. FIG. 13 is a schematic diagram for illustratingan active device array substrate 310 according to the third embodimentof the present invention. Referring to FIG. 13, a first pixel electrodeP1 has an area 0.2 to 0.8 times that of the second pixel electrode P2.In such a way, charging ratios of the first pixel electrode P1 and thesecond pixel electrode P2 are different from each other.

In summary, the present invention provides an active device arraysubstrate. The active device array substrate may have a first pixelelectrode and a second pixel electrode having different surface areas.Alternatively, the active device array substrate may employ a firstresistant device disposed on the substrate and electrically connectedbetween the first active device and the first pixel electrode.Therefore, the first pixel electrode and the second pixel electrode havedifferent voltages after being charged such that the transmittancescorresponding to the first pixel electrode and the second pixelelectrode respectively can be different. Thus, two differenttransmittances can compensate one to another such that a viewing effectsimilar to a frontal view can be achieved regardless of viewing anglesthrough. Accordingly, the LCD panel according to the present inventionhas a better displaying quality. Alternatively, a second resistantdevice, and a shielding metal layer under the second resistant devicemay also be employed to adjust the charging ratios of the first pixelelectrode and second pixel electrode.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. An active device array substrate, comprising: asubstrate; a plurality of scan lines, disposed over the substrate; aplurality of data lines, disposed over the substrate; and a plurality ofpixel units, disposed over the substrate, each of the pixel units formedbetween every neighboring two of the scan lines and data lines, and eachof the pixel units comprising: a first active device; a first pixelelectrode, electrically connected to a corresponding scan line and acorresponding data line through the first active device; a second activedevice; and a second pixel electrode, electrically connected to thecorresponding scan line and the corresponding data line through thesecond active device, wherein the first pixel electrode has a surfacearea different from that of the second pixel electrode.
 2. The activedevice array substrate of claim 1, wherein a surface area of the firstpixel electrode is 0.2 to 0.8 times that of the second pixel electrode.3. An liquid crystal display panel, comprising: the active device arraysubstrate as claimed in claim 1; an opposite substrate, disposed overthe active device array substrate; and a liquid crystal layer, disposedbetween the active device array substrate and the opposite substrate. 4.The liquid crystal display panel of claim 3, wherein the oppositesubstrate is a color filter substrate.
 5. The liquid crystal displaypanel of claim 3, wherein a surface area of the first pixel electrode is0.2 to 0.8 times that of the second pixel electrode.
 6. An active devicearray substrate, comprising: a substrate; a plurality of scan lines,disposed over the substrate; a plurality of data lines, disposed overthe substrate; and a plurality of pixel units, disposed over thesubstrate, each of the pixel units formed between every neighboring twoof the scan lines and data lines, and each of the pixel unitscomprising: a double drain active device, comprising a first activedevice and a second active device; a first pixel electrode, electricallyconnected to a corresponding scan line and a corresponding data linethrough the first active device of the double drain active device; and asecond pixel electrode, electrically connected to a corresponding scanline and a corresponding data line through the second active device ofthe double drain active device, wherein the first pixel electrode has asurface area different from that of the second pixel electrode and asurface area of the first pixel electrode is 0.2 to 0.8 times that ofthe second pixel electrode.
 7. An liquid crystal display panel,comprising: the active device array substrate as claimed in claim 6; anopposite substrate, disposed over the active device array substrate; anda liquid crystal layer, disposed between the active device arraysubstrate and the opposite substrate.
 8. The liquid crystal displaypanel of claim 7, wherein the opposite substrate is a color filtersubstrate.